What quantum readiness means
A cryptographically relevant quantum computer (CRQC) would break RSA, Diffie-Hellman and elliptic-curve cryptography. Those algorithms protect TLS, VPNs, digital signatures, PKI, payments and identity. Quantum readiness is not about owning quantum technology. It is about removing that dependency on time.
A quantum-ready organisation can answer four questions with evidence:
- Where do we use quantum-vulnerable cryptography, including inside our vendors?
- Which of those uses put sensitive, long-lived data or critical operations at risk?
- What is our plan, timeline and budget to migrate them to post-quantum cryptography?
- How far along are we, and how do we know?
Why it is urgent: Mosca's theorem
Professor Michele Mosca's rule of thumb frames the timing: if X (how many years your data must stay confidential) plus Y (how many years your migration will take) is greater than Z (years until a CRQC exists), your data is already at risk.
Take a bank with customer records that must stay confidential for 10 years and a realistic 5-year migration. That bank needs 15 years of safety, which is longer than many expert estimates for Z. Adversaries harvesting encrypted traffic today (harvest now, decrypt later) make X the real exposure window. That is why regulators ask for readiness now, not when a quantum computer is announced.
The quantum readiness maturity model
Use a five-level model to baseline your current state and track improvement quarter by quarter:
| Level | What it looks like |
|---|---|
| Level 1 — Unaware | No inventory, no owner. Quantum risk is not on the risk register. |
| Level 2 — Aware | Leadership understands the risk. Discovery has started but is partial and manual. |
| Level 3 — Inventoried | A complete cryptographic inventory exists, including vendors, and risk is scored. |
| Level 4 — Migrating | A funded roadmap is in execution. Hybrid PQC is deployed on priority systems and vendor requirements are in contracts. |
| Level 5 — Crypto-agile | Cryptographic posture is monitored continuously, algorithms can be swapped through configuration, and evidence is audit-ready. |
Most organisations today sit at Level 1 or 2. Regulated organisations should target Level 3 now and Level 4 on priority systems before 2030.
Quantum readiness checklist
Visibility
- Cryptographic inventory covers cloud, on-prem, applications, certificates, keys and HSMs
- SaaS and software vendors are included, not only internal systems
- The inventory updates continuously rather than once a year
Risk
- Assets are mapped to data classification and required confidentiality lifetime
- Internet-facing and third-party exposure is flagged
- Findings are scored and ranked by business impact
Agility
- Hybrid ML-KEM key exchange is tested or enabled on priority TLS endpoints
- Algorithms are configurable rather than hard-coded
- PKI, CA and HSM vendors have published post-quantum roadmaps
Governance
- A named owner and a board-level reporting line exist
- A post-quantum cryptography policy and target algorithms (FIPS 203/204/205) are defined
- Procurement contracts require vendors to disclose their PQC plans
- Audit-ready evidence of posture and progress is available on demand
A 90-day plan to become quantum-ready
- Days 1–30: Baseline. Assign ownership, run a quantum readiness assessment and start automated discovery. Begin with your SaaS vendors and internet-facing assets.
- Days 31–60: Prioritise. Complete the inventory for critical business services, score risk by data lifetime and exposure, and identify quick wins such as enabling hybrid key exchange where your providers already support it.
- Days 61–90: Commit. Publish a PQC migration roadmap with owners and dates, add PQC clauses to vendor contracts, and set up ongoing posture reporting for leadership and auditors.
Proving quantum readiness to auditors and customers
Quantum readiness is fast becoming a sales and audit requirement. Enterprise security questionnaires, PCI DSS v4.0 (requirement 12.3.3 on cryptographic inventories), DORA's cryptographic controls and national PQC roadmaps all ask the same thing: show us your inventory, your prioritised plan and your progress.
PQCLayer is built to produce that evidence. It inventories cryptographic assets across cloud, enterprise systems and software vendors, prioritises risk by business impact, and tracks remediation over time. This is the continuous discipline of crypto posture management. To see where you stand today, run a free scan.
Frequently asked questions
What is quantum readiness?
Quantum readiness is an organisation's ability to keep its data, identities and transactions secure once cryptographically relevant quantum computers exist. In practice it means knowing where quantum-vulnerable cryptography is used, having a prioritised plan and budget to migrate to post-quantum cryptography, and being able to prove progress to auditors, regulators and customers.
How do you measure quantum readiness?
Measure it across four dimensions: visibility (how complete and current your cryptographic inventory is), risk (whether exposure is scored by data lifetime and business impact), agility (how quickly algorithms can be changed), and governance (ownership, policy, vendor requirements and audit evidence). A maturity model with levels from ad hoc to optimised makes the score comparable over time.
What is a quantum readiness assessment?
A quantum readiness assessment is a structured review that produces a baseline score, identifies the highest-risk cryptographic dependencies, and outputs a prioritised roadmap and timeline for post-quantum migration. PQCLayer offers a free online readiness assessment that returns an initial score, recommendations and a rough readiness timeline.
When do organisations need to be quantum-ready?
Most roadmaps target 2030 to 2035. NIST IR 8547 proposes deprecating quantum-vulnerable public-key algorithms after 2030 and disallowing them after 2035, and the UK NCSC expects high-priority migrations by 2031. Because of harvest-now-decrypt-later attacks, data that must remain confidential beyond that window is already at risk.
What is Mosca's theorem?
Mosca's theorem is a rule of thumb for quantum risk: if X (how long your data must stay secure) plus Y (how long migration will take) is greater than Z (the time until a cryptographically relevant quantum computer exists), you are already late. It is a simple way to explain quantum readiness urgency to executives.